Abstract
BACKGROUND & AIMS: This study was performed to improve the autofluorescence imaging (AFI) in the upper GI tract by applying a new method of normalized autofluorescence (NAFI) obtained via tri-modal imaging. OBJECTIVE: NAFI may provide lower false positive rate to achieve ultimately better specificity at acceptable sensitivity. PATIENTS AND METHODS: This is a prospective, controlled single-centre study. 18 patients with suspected esophagus or stomach cancer undergoing esophagogastroduodenoscopy (EGD) were enrolled between February and May 2010. After endoscopy each patient was assigned into one of two groups: (1) non-cancer, including inflammation; (2) cancer group. EGDs were performed using video white light endoscopy, followed by AFI/NAFI. The targeted biopsy samples were taken from the abnormal areas as well as from adjacent mucosa. NAFI was compared versus AFI for cancer diagnostics in terms of specificity and sensitivity. RESULTS: NAFI detected all neoplastic lesions. WLE or NBI detected no additional neoplasia. The AFI displayed mucosal inflammation and carcinomas of esophagus and stomach as dark red color, the normal mucosa background was displayed as light green. The NAFI didn't differentiate inflamed tissue from normal in majority of cases, but in tumorous mucosa, the cancer areas were detected precisely. AFI shows 100% sensitivity but 50% specificity which correlates with previous literature data. On the other hand, NAFI demonstrated lower sensitivity (88%) but higher specificity compared to AFI (69%). CONCLUSIONS: Measuring the NAFI instead of the AFI was found improving the specificity of cancer diagnosis. Use of fiber-optic endoscopes to analyze AFI and possible endoscopic and histological sampling error are the main potential limitations of this method.